1. Field of the Invention
The present invention relates to an improved continuous coupling element row, which is made of a synthetic resin, for a slide fastener, and to a surface treating method for the coupling element row.
2. Description of the Prior Art
Conventionally, a continuous coupling element row, which is made of a synthetic resin, for a slide fastener on which a metallic material is deposited for purposes of decoration is commonly known. In such a product the deposition of the metallic material is accomplished by means of a plating process. The plating process requires a large number of processing stages in each of which the coupling element row must be fed horizontally into a chemical bath for treatment. Therefore, a tension load is applied to the coupling element row along its length when it is subjected to the conventional plating process. As a result, the pitch of the coupling element row tends to be distorted and its function as a slide fastener is impaired. Throughout the specification, the term "pitch" is used to mean a "spacing between adjacent coupling elements".
In addition, the metallic material is merely deposited on the surface of the coupling element row in the form of a film, and the film itself is hard and is not flexible. Therefore, when the coupling element row is bent, the deposited metallic material is easily cracked. When the motion of the slider is added to the slide fastener having such cracks, exfoliation of the metallic film occurs over a wide range and the external appearance of the product becomes unsightly.